This invention relates to an electronic musical instrument and, in particular, an electronic musical instrument arranged to simulate a struck-string instrument.
In a known electronic musical instrument arranged to simulate a struck-string instrument such as a piano, a plurality of tone signals are amplitude-modified in accordance with the shapes of different envelope signals as generated in response to the depression of one key. The amplitude-modified tone signals have their frequency spectra modified by tone coloring filters having different frequency characteristics, and the frequency spectrum-modified tone signals are mixed together. The mixed output has an amplitude proportional to a key depression speed as in the case of a struck-string instrument and has a frequency spectrum varied with time during the time interval from the build-up to the decay of the signal. Namely, in the conventional electronic musical instrument, different envelope signals are required to produce a tone signal having a frequency spectrum varied with time.
The conventional electronic musical instrument is so constructed that circuits for modifying the amplitude of tone signals are adapted to receive different envelope signals. When, therefore, amplitude modification circuits are integrated on the same semiconductor chip, the terminals of an integrated circuit package are increased in number. An arrangement in which different envelope signals are generated in response to the depression of one key is unsuitable for an integrated circuit version of an instrument. A circuit arrangement for generating a plurality of envelope signals by the depression of one key makes the construction of an electronic musical instrument complicated.